Dye Sensitization Offers a Brighter Afterglow Nanoparticle Future for in vivo Recharged Luminescent Imaging

While concerns about improving recharged afterglow intensity in vivo still motivate further exploration, afterglow nanoparticles (AGNP) offer unique optical merit for autofluorescence-free biological imaging. Apart from efforts enhancing the afterglow emission properties of AGNP, improving afterglow excitation response to visible or near infrared light is important but has lacked success. Dye sensitization has been used to improve the optical response of photovoltaic nanomaterials and to enhance upconversion luminescence efficiency. This concept has recently been expanded and applied to AGNPs. As a new multifunctional nanoprobe, such dye-sensitized AGNP takes advantage of both high spatial resolution fluorescence imaging and sensitive afterglow imaging. This Concept introduces the background, the concept, mechanism, and related imaging application, as well as reviewing existing challenges and proposing future developmental directions for the dye-sensitized AGNPs.     

Chlorophyll sensitized BiVO4 as photoanode for solar water splitting and CO2 conversion

Converting solar energy into valuable hydrogen and hydrocarbon fuels through photoelectrocatalytic water splitting and CO_2 reduction is highly promising in addressing the growing demand for renewable and clean energy resources. However, the solar-to-fuel conversion efficiency is still very low due to limited light absorption and rapid bulk recombination of charge carriers. In this work, we present chlorophyll(Chl) and its derivative sodium copper chlorophyllin(ChlCuNa), as dye sensitizers, modified BiVO_4 to improve the photoelectrochemical(PEC) performance. The photocurrent of BiVO_4 is surprisingly decreased after a direct sensitization of Chl while the sensitization of ChlCuNa obviously enhances photocurrent of BiV04 electrodes by improved surface hydrophilicity and extended light absorption.ChlCuNa-sensitized BiV04 achieves an improved H_2 evolution rate of 5.43 μmol h~(-1) cm~(-2) in water splitting and an enhanced HCOOH production rate of 2.15 μmol h~(-1) cm~(-2) in CO_2 PEC reduction, which are1.9 times and 2.4 times higher than pristine BiVO_4, respectively. It is suggested that the derivative ChlCuNa is a more effective sensitizer for solar-to-fuel energy conversion and CO_2 utilization than Chl.     

叶绿素敏化二氧化钛纳米管电极光电性能及其增强机理

为了研究叶绿素的敏化机理,本文以菠菜叶片叶绿素的乙醇浸提液敏化纳米管TiO_2电极,在Na2SO4水溶液电解液中测定其光电性能。敏化电极的光电流响应曲线显示,叶绿素浸提液敏化纳米管TiO_2电极时会显著改变电极的光电流值,而敏化Ti电极时则产生光电流极小。电极的循环伏安曲线则表明,叶绿素浸提液使电极上的氧化反应更容易发生。测定不同浓度的叶绿素浸提液敏化纳米管TiO_2电极的单色光光电转化效率(IPCE)图谱,结果表明,合适的叶绿素浓度(7.123~71.23μg/L)使电极IPCE平均增加2倍以上,但浓度增大至7123μg/L时,其敏化电极IPCE则明显降低;同时发现叶绿素的敏化作用未明显改变TiO_2电极IPCE图谱的特征谱峰位置。根据实验数据和结果,得出在水溶液中叶绿素改变纳米管TiO_2光电性能的机理,主要是通过叶绿素分子与TiO_2电极中的光生空穴发生反应,进而减少光生电子与空穴的复合,使电极有效光生电子数量增加,光电流密度增大,最终提高TiO_2电极的IPCE。     

Computational studies on optoelectronic and charge transfer properties of some perylene‐based donor‐π‐acceptor systems for dye sensitized solar cell applications

We report DFT studies on some perylene‐based dyes for their electron transfer properties in solar cell applications. The study involves modeling of different donor‐π‐acceptor type sensitizers, with perylene as the donor, furan/pyrrole/thiophene as the π‐bridge and cyanoacrylic group as the acceptor. The effect of different π‐bridges and various substituents on the perylene donor was evaluated in terms of opto‐electronic and photovoltaic parameters such as HOMO‐LUMO energy gap, λ_max, light harvesting efficiency(LHE), electron injection efficiency (Ø_inject), excited state dye potential (E^dye*), reorganization energy(λ), and free energy of dye regeneration (). The effect of various substituents on the dye–I₂ interaction and hence recombination process was also evaluated. We found that the furan‐based dimethylamine derivative exhibits a better balance of the various optical and photovoltaic properties. Finally, we evaluated the overall opto‐electronic and transport parameters of the TiO₂‐dye assembly after anchoring the dyes on the model TiO₂ cluster assembly.     

Visible Light Photocatalytic Activity of Porphyrin Tin(IV) Sensitized TiO2 Nanoparticles for the Degradation of 4-Nitrophenol and Methyl Orange

A stable metalloporphyrin sensitized TiO₂ (Degussa P25) photocatalyst was prepared by using trans-dihydroxo[5,10,15,20-tetraphenylporphyrin]tin(IV) (SnP) as a sensitizer in a simple impregnation process. The solid diffuse reflectance ultraviolet-visible (UV-vis) spectrum of the SnP sensitized TiO₂ photocatalyst (SnP-TiO₂) indicated that there existed interaction between SnP and TiO₂. It was found that SnP-TiO₂ exhibited an enhanced visible light photocatalytic activity as compared with that over P25 for the degradation of 4-nitrophenol (4-NP) and methyl orange (MO) in aqueous solutions. The mechanism exploration showed that the degradation of MO and 4-NP experienced two different ways, that is, MO was photodegraded by reactive oxygen species and 4-NP was directly photodegraded by the excited state of SnP. Furthermore, it was found that the loading content of SnP had an important influence on the photocatalytic activity of TiO₂. The maximum photocatalytic efficiency was achieved when the contents of SnP were 25 mg and 30 mg per gram TiO₂ for MO and 4-NP, respectively. Importantly, SnP-TiO₂ was particularly stable and the photocatalytic activity was hardly decreased after being recycled seven times in the presence of oxygen, which could be attributed to the easy reductive regeneration of SnP.     

Building an Iron Chromophore Incorporating Prussian Blue Analogue for Photoelectrochemical Water Oxidation

The replacement of traditional ruthenium-based photosensitizers with low-cost and abundant iron analogs is a key step for the advancement of scalable and sustainable dye-sensitized water splitting cells. In this proof-of-concept study, a pyridinium ligand coordinated pentacyanoferrate(II) chromophore is used to construct a cyanide-based CoFe extended bulk framework, in which the iron photosensitizer units are connected to cobalt water oxidation catalytic sites through cyanide linkers. The iron-sensitized photoanode exhibits exceptional stability for at least 5 h at pH 7 and features its photosensitizing ability with an incident photon-to-current conversion capacity up to 500 nm with nanosecond scale excited state lifetime. Ultrafast transient absorption and computational studies reveal that iron and cobalt sites mutually support each other for charge separation via short bridging cyanide groups and for injection to the semiconductor in our proof-of-concept photoelectrochemical device. The reorganization of the excited states due to the mixing of electronic states of metal-based orbitals subsequently tailor the electron transfer cascade during the photoelectrochemical process. This breakthrough in chromophore-catalyst assemblies will spark interest in dye-sensitization with robust bulk systems for photoconversion applications.     

Effect of Mie resonance on photocatalytic hydrogen evolution over dye-sensitized hollow C-TiO_2 nanoshells under visible light irradiation

Light utilization is one of the key factors for the improvement of photocatalytic perfo rmance.He rein,we design C-TiO_2 hollow nanoshells with strong Mie resonance for enhanced photocatalytic hydrogen evolution in a dye-sensitized system under visible light irradiation(λ≥420 nm).By tuning the inner diameters of hollow nanoshells,the Mie resonance in hollow nanoshells is adjusted for better excitation of dye molecules,which thus greatly enhances the light utilization in visible light region.This work shows the potential of Mie resonance in nanoshells can be an alternative strategy to increase the light utilization for photocatalysis.     

Fluorescence Sensitization of Aqueous Terbium and Europium Ions Without Aromatic Donors or Synergistic Agents

Abstract

EDTA and DTPA complexes of terbium and europium are excited at wavelengths below 250 nm. producing the typical lanthanide emission through energy transfer from the complex to the coordinated metal. This allows determination of these rare earth ions in water without solvent extraction, the use of synergistic agents, or aromatic sensitizers. Terbium-EDTA has the most efficient energy transfer, 31%, giving a 165-fold emission enhancement and a limit of detection of 6 × 10^?7 M. Calibration curves are linear over a concentration range spanning three orders of magnitude. The characteristic lanthanide ion emission is obtained in all cases, but the excitation of the complexes is pH dependent, showing intensity increases up to pH 12. Mild interference by alkali and alkaline earth metals was overcome by increasing the ligand concentration, but transition metal interference was more severe. Only minor enhancement was observed at higher ligand/metal ratios.     

硫化亚铜对电极在量子点敏化太阳电池中的应用

报道了一种基于硫族金属复合物N₄H₉Cu₇S₄前驱体溶液制备硫化亚铜对电极的新方法. 分别制备了TiO₂纳米颗粒多孔薄膜和TiO₂纳米棒阵列结构的光阳极, 并在此基础上研究了基于硫化亚铜对电极的CdS/CdSe量子点敏化太阳电池的光电性能, 同时结合电化学阻抗技术考察了硫化亚铜对电极的催化性能. 结果表明: 与铂电极相比, 本方法制备的硫化亚铜电极对多硫电解质具有更高的催化活性, 所组装的CdS/CdSe量子点敏化太阳电池具有更优的光伏性能.     

Ag-Ag2Se共敏化ZnO花-棒异质结构的合成及其光电化学特性

采用水相法合成ZnO花-棒(ZFRs)有序阵列结构,同时利用离子交换法,制备Ag和Ag₂Se量子点共敏化光ZnO光阳极(AA-ZFRs)。通过扫描电子显微镜(SEM)、X射线粉末衍射(XRD)、X射线能量色散谱(EDS)和透射电子显微镜(TEM)等手段对样品进行了分析和表征,并测试其光电化学特性以及量子效应。结果表明,Ag-Ag₂Se共敏化ZnO花-棒三维有序结构对太阳光的吸收范围延展至近红外区(750 nm),并且在敏化层与ZnO基质界面形成异质结,有效的抑制光生电子-空穴对复合,增强光转换量子效应,从而提高光电化学性能,开路电压达到-0.77 V,短路电流为0.64 mA。